WASHINGTON -- Immediate reaction to President Obama’s surprise announcement that he would seek congressional authorization for a military strike on Syria was largely positive among members of Congress, but offered little indication of whether a vote would succeed.

Congressional approval could prove difficult, as conservatives and liberal Democrats have expressed uneasiness with a military campaign.

About 200 members of Congress from both parties had signed letters demanding that the president seek congressional approval before pursuing any military action.

After Obama finished outlining his intentions in the White House Rose Garden, Sen. Bob Corker of Tennessee, the ranking Republican on the Senate Foreign Relations Committee, said in a statement that he was "very pleased that the president has listened to the suggestion we and many others have made to bring this authorization to Congress."

Corker, who has spoken in support of a military strike, said it was now "imperative that he immediately begins using every ounce of his energy to make his case to the American people."

“We are glad the president is seeking authorization for any military action in Syria in response to serious, substantive questions being raised,” House Speaker John Boehner (R-Ohio) said in a statement. “ In consultation with the president, we expect the House to consider a measure the week of September 9th. This provides the president time to make his case to Congress and the American people.”

Senate Minority Leader Mitch McConnell (R-Ky.) signaled his support for Obama’s decision, saying in a statement that "the president’s role as commander-in-chief is always strengthened when he enjoys the expressed support of the Congress."

Congress is on an extended summer break and is not scheduled to return to Washington until the second week of September. Earlier Saturday, the Senate’s No. 2 Republican, Sen. John Cornyn of Texas, said in a statement, “Before any military action is taken in Syria, the president should call Congress back into session and ask for a vote on the authorization to use force.”

Obama administration officials plan to brief the full membership of Congress this weekend, the first such expanded briefing for lawmakers since the Aug. 21 chemical weapons attack blamed on the Syrian government that killed 1,400 people, including at least 426 children.

A spokesman for Sen. Mitch McConnell (R-Ky.) said the Senate minority leader requested the call for Senate Republicans, saying that it was "important for the whole conference to have the opportunity to communicate directly with the administration on this important issue."

Members of the House have also been invited to an in-person briefing on Sunday at the Capitol, which congressional sources also said came at the request of the House leadership. It is unclear how many members of the House would return to Washington for the briefing.

So far, only the congressional leadership and members of committees with jurisdiction over national security have participated in administration briefings.

On Thursday, 26 members of Congress took part in a more than 90-minute call with White House officials. Members of the Senate Foreign Relations Committee and Armed Services Committee were briefed on Friday.

Rep. Justin Amash (R-Mich.), one of the strongest congressional voices demanding an authorization vote, quickly posted on his Twitter account: "Thank you, Mr. President." He later added that it was "unfortunate" he had to thank the president "for following the Constitution and the law."